1. Field of the Invention
The present invention pertains to an anti-vibration actuator, and more particularly to an anti-vibration actuator furnished with a locking mechanism for executing anti-vibration control by moving an image-blur prevention lens, a lens unit and camera furnished therewith, and a manufacturing method for same.
2. Description of Related Art
A “Vibration Compensation Device” is set forth in Published Unexamined Patent Application H.10-260445 (Patent Document 1). This vibration compensation device is furnished with an affixing means (locking mechanism) for locking an image-blur prevention lens to prevent image blurring. In this vibration compensation device, an affixing means is engaged with a lens frame for an image-blur prevention lens when under non-image-blur prevention control in which vibration compensation is not carried out, thereby locking the image-blur prevention lens in a predetermined position. The affixing means is a ring-shaped member disposed to surround the lens frame of the image-blur prevention lens which is rotated when locking the lens frame, and the lens frame is mechanically locked when the inner circumferential surface of the affixing means engages projections provided on the lens frame.
Here, even if the lens frame is in a mechanically locked state, some looseness (“play”), which is unavoidable with a mechanical lock, is required, and in general the movable portion of a lens frame or the like is able to move on the order of several 10s of microns even in a locked state. In general, however, the position of the image-blur prevention lens is controlled with a resolution of approximately several microns during image-blur prevention control, and movement of the lens frame caused by “looseness” in the locked state greatly affects the quality of captured images. Therefore in an image-blur compensation device (anti-vibration actuator) it is necessary to minimize as much as possible the amount of movement caused by “looseness” in the movable portions such as the of the lens frame, etc. in the locked state.
On the other hand, in anti-vibration actuators having a locking mechanism, in general a drive force is first activated on the movable portion such as the lens frame or the like and the movable portion is held to a predetermined initial position when image-blur prevention control is started, and thereafter locking of the movable portion by the locking mechanism is released. I.e., when locking of the movable portion is released prior to activating a drive force on the movable portion and holding a position, the movable portion drops due to gravity, the image-blur prevention lens is significantly moved, and the image formed in the finder is greatly distorted. Therefore in an anti-vibration actuator drive force is generally applied to the movable portion and the lock released immediately after holding the movable portion at the initial position.